The present disclosure relates to adhesive compositions, and, more specifically, to biomimetic adhesive compositions and their use in a subterranean formation.
Biological organisms are well known for their ability to construct a wide breadth of biomaterials, many of which have properties that are unrivaled by their synthetic counterparts. As used herein, the term “biomaterial” refers to a substance that is synthesized by a biological organism. Biomaterials can be used for a wide variety of purposes by biological organisms including, for example, support and protection (e.g., endoskeletons, exoskeletons, shells, and like biomineralized structures), trapping of prey (e.g., spider webs), locomotion, and surface adhesion. Self-assembly may play a role in the formation of many of these biomaterials. As used herein, the term “self-assembly” refers to the spontaneous organization of substances to form stable, well-organized, structurally defined arrays without the influence of external forces.
Study of the structure of biomaterials can provide the inspiration for designed synthetic materials. In some cases, a synthetic material can attempt to replicate the structure of a biomaterial. In other cases, a synthetic material can have a significantly different structure than the parent biomaterial, but still incorporate a structural element therefrom, sometimes in modified form. Structurally modified synthetic materials that retain a structural element or modified structural element of a parent biomaterial are often referred to as “biomimetic materials.” Modification of the parent biomaterial structure, as in biomimetic materials, may be beneficial when the parent biomaterial is unsuitable for an intended application due to undesirable properties such as, for example, cost, stability, mechanical properties, physical properties, chemical properties, and the like.
Adhesive compositions, in particular, are ubiquitous among biological organisms due to their ability to effectively function in a variety of environments. Marine mussels and other marine organisms, in particular, are known for their ability to secrete adhesive proteins (bioadhesives) that can form a coacervate in the mussels' aqueous habitat. As used herein, the term “coacervate” refers to an agglomeration of crosslinked molecules that adjoins two or more surfaces. Most typically, these adhesive proteins comprise a DOPA (3,4-dihydroxyphenylalanine) or like catechol-type moiety within the polymer structure. Without being bound by any theory or mechanism, it is believed that catechol-type moieties are susceptible to oxidation, particularly in the presence of transition metal ions, thereby forming an o-quinone, which ultimately undergoes a crosslinking reaction with another catechol-type moiety. The presumed crosslinking reaction is shown in Scheme 1 below.
Although these types of adhesive proteins and others can be easily synthesized by biological organisms, such proteins represent a much greater challenge for commercial production and field applications in terms of synthetic difficulty and cost. Furthermore, protein-derived biomaterials may provide poor stability at elevated temperatures and/or in certain types of chemical environments.
Given the beneficial properties of bioadhesives, it would be desirable to apply similar adhesives in a non-biological setting, particularly in environments where traditional adhesives may be less adherent or have insufficient strength, such as in aqueous environments. As noted above, in non-biological settings, protein molecules can present considerable synthetic and economic challenges that may prohibit their successful implementation. DOPA-containing proteins may be particularly challenging in this regard. Not only is DOPA very expensive, but chemical instability of its catechol moiety can make synthetic manipulations difficult.
Subterranean treatment operations are one field application where it can sometimes be desirable to utilize adhesive compositions. Adhesive compositions can be used in subterranean formations, for example, to consolidate a loosely consolidated formation, to improve structural integrity of the wellbore, to consolidate a particulate pack (e.g., a proppant pack or a gravel pack) in the subterranean formation, to control the production of fines, and the like. Aqueous tackifying agents, non-aqueous tackifying agents, curable resin tackifying agents, and non-curable and non-aqueous tackifying agents can be used in this regard in subterranean treatment operations. Although these tackifying agents and others can often be successfully used in subterranean treatment operations, there may still be certain applications in which they are chemically unstable or are otherwise difficult to deploy operationally. Furthermore, some components of traditional adhesive compositions can present challenges from the standpoint of biodegradability or environmentally acceptability.